High velocity multi-stage guns



Dec. 19, 1961 KAI-[N HAL 3,013,472

HIGH VELOCITY MULTI-STAGE GUNS Filed Dec. 4, 1958 25 27 INVENTORSJ FIG 4 HENRY KAHN WILLIAM J. KROEGER WILLIAM DITTRICH ATTORNEYS:

r 3,013,472 Patented Dec. 19, 1961 3,013,472 HIGH VELOCITY MULTI-STAGE GUNS Henry Kahn, Levittown, William J. Kroeger, Philadelphia, and William Dittrich, Abington, Pa., assignors to the United States of America as represented by the Secretary of the Army Filed Dec. 4, 1958, Ser. No. 778,268 1 Claim. (Cl. 89--1.7) (Granted under Title 35, U.S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to us of any royalty thereon.

This invention relates to ammunition wherein a plurality of projectiles or masses are each followed by a different explosive charge, and to a gun wherein these charges are ignited successively so that there is imparted to the final projectile a higher velocity than is otherwise attainable.

Using conventional interior ballistic techniques, there is a velocity limit in weapons in the vicinity of 5000 feet per second. This is true both of recoilless rifles and of conventional closed breech rifles. Thus in the case of conventional closed breech weapons, the ratio of propellant charge to projectile mass c/ m) increases very rapidly as the velocity approaches and exceeds 5000 feet per second. In the case of recoilless weapons, this increase is even greater because of the extra gas required for momentum cancellation. A great deal of the mechanical energy generated just goes into gas motion and only an even lesser part becomes available for projectile motion as velocity is increased.

Since the weight of the weapon is directly related to the total mechanical energy generated, the design cannot be very efl'icient, from the weight standpoint, for high velocity weapons. This increase in weapon weight and size becomes apparent in several of the recently proposed high velocity guns. Some methods have been proposed for increasing velocity. One is to use a lighter gas which travels at a higher velocity. Propellants capable of generating such a gas are difficult to obtain and use. This leaves without a satisfactory solution the problem of attaining high velocities without undue increase in the weight of the gun.

In accordance with the present invention this problem is solved by the provision of (1) a cartridge including a plurality of masses each having at its rear a different explosive charge and (2) a gun which functions to fire these charges at successive predetermined times. Thus during their travel in the gun barrel, the different charges are successively ignited accelerating each of the masses with States Patent Ofifice mass or projectile 16. The barrel 10 has an enlarged-section 17 which is arranged to bypass gas for igniting the second charge 15 at a predetermined point in the travel of the projectile 16. V

In the operation of this rifle, the first charge may have an electric primer which is fired by a voltage applied through a lead 18. Burning of the charge 13 produces a gas under pressure which accelerates the piston 14, the charge 15 and the projectile 16 as a single unit to a point shortly after the peak acceleration (peak-pressure). This point is reached fairly early in the travel of the projectile. At this point, the piston 14 is in the enlargement 17 and is bypassed by the hot gas which fires the second charge 15 thus accelerating the projectile 16 with respect to the piston 14.

The burning of the second bed of propellant provides a source of gas at the base of the projectile. The pressure in this region is maintained by the action of the piston as it accelerates in the forward direction. The projectile thus receives increments of momentum ordinarily lost in a conventional ballistic system.

FIGS. 2 and 3 illustrate a type of ammunition wherein the piston 14 is threaded onto a rod 18a, is fixed to the rod by locknuts 19 and 20, and has a plurality of longitudinal apertures 21 each associated with a nozzle 22. Threaded to the rod 18 is a spider 23 to which the projectile 16 is press fitted or otherwise releasably attached. In the use of this ammunition, gas generated by the firing of the charge 13 not shown in FIG. 2) is passed through nozzles 22 and apertures 21 for igniting the second charge 15 whereupon the projectile is detached from the spider 23 and is projected from the rifle barrel as indicated in connection with the previous figures.

FIG. 4 illustrates a form of ammunition which functions to fire the second charge 15 electrically at a predetermined point in the travel of the projectile 16. To this end, there is provided between the piston 14 and the projectile 16a tube 24 which is perforated and contains a powder for igniting the second charge 15. The igniting powder in the tube 24 is fired by an electric primer 25 which is connected to a contact plate 26 through a rod 27. The rod 27 is electrically insulated from the projectile 16 by a collar 28 and the contact plate is similarly insulated by a Washer 29. Under these conditions, one terminal of the primer 25 is conductively associated with the barrel ,1!)

' and the other is connected to the plate 26 and insulated respect to the mass immediately following it. Since the reference of each mass is the preceding mass, the velocity limit is theoretically the velocity of sound in the propellant gas multiplied by the number of stages.

The invention will be better understood from the following description when considered in connectionwith the accompanying drawings and its scope is indicated by the appended claim.

Referring to the drawings:

FIG. 1 illustrates a form of the invention wherein gas generated by the firing of the first charge is shunted around the first mass to ignite the second charge,

FIGS. 2 and 3 show a type of ammunition wherein the gas generated by the firing of the first charge is transmitted through the first mass to fire the second charge, and

FIG. 4 illustrates a form of ammunition wherein the second charge is fired electrically.

FIG. 1 illustrates a recoilless rifle which includes a barrel 10, a chamber 11, and a venturi 12. The ammunition arranged to be fired by this rifle includes a first charge 13, a first mass or piston 14, a second charge 15 and a second from the barrel.

Extending into the path of the plate 26 is a contact 30 which is supported in a plug 31 and is insulated from the barrel 10 by a collar 32/ Connected between the barrel 10 and the contact 30 are a 2500 volt source 33 and a 100,000 ohm resistor 34, this source and resistor being shunted by a capacitor 35. With these connections, the circuit of the primer 25 is completed and the second charge 15 is fired when the plate .26 engages the contact 30.

This modification of the invention, like those previously described, functions to accelerate the projectile to a higher velocity than can be realized with a conventional weapon. This result is attained Within reasonable travel limits and without undue increase in the weight of the weapon. While one piston and two charges havebeen described, it is to be understood that the number of pistons and charges. utilized is dependent on the final velocity to be imparted to the projectile.

Those familiar with recoilless guns and their operation will appreciate how this invention has special advantages in guns of this type and these include:

(a) The attainment of a higher velocity more efficiently than can be obtained otherwise in guns of this type and without undue increase in weight of the weapon.

(b) The erosion of the venturi constricted throat portion has long been known to be a serious problem afiecting the useful life of a recoilless gun, but under this invention that erosion may be greatly reduced for a given velocity of projectile because the piston 14 prevents much of the propelling gas at high pressure from eroding the venturi.

(c) A piston 14 in rear of a forward projectile niay be less of a hazard in recoilless than in recoilling guns because of the big gas movement rearward, which may be of a size to avoid ejecting the first piston since that inevitably acts to absorb much of the energy in the second charge that would otherwise be vented through the venturi opening.

An advantage in the FIG. 1 embodiment is that as shown in the drawing the internal diameter of the enlargement 17 is more than twice the internal diameter of the barrel 10 so that igneous gases from the first charge 13 may pass around the piston 14 for 360. This means that any portions of such burning gases contiguous to the inner wall of the enlargement and contiguous to the outer surface of the piston may be chilled by contact with these relatively cold surfaces, without causing the hot flames intermediate and out of contact with these surfaces from being adequately heated to fire the second charge 15 with reliability. Locating the enlargement 17 well forward of the projectile 16 when positioned in the gun before firing enables the second charge 15 to be fired only after the piston 14 and projectile have moved forward a predetermined distance in said barrel.

We claim:

A recoilless gun having a barrel, a venturi passageway 30 gun in front of said venturi passageway, a piston slidably fitting within said barrel in front of said charge to be moved by firing said charge, a second explosive charge in front of said piston, a projectile in front of said second charge, means for firing the first mentioned explosive charge, and moving said piston, second charge and projectile forward, and means for firing said second charge after a predetermined forward movement by said piston, second charge and projectile, said means for firing said second charge including an enlargement in said barrel of a length substantially in excess of the length of said piston, said enlargement having an inside diameter at least about twice that of said piston and internal diameter of the gun barrel to enable flames from said first charge to pass around said piston on all sides thereof when the piston has advanced beyond a rear end of said enlargement for igniting a rear portion of and said second charge within said enlargement, whereby higher muzzle velocities are attainable, said enlargement being located forward of the projectile when positioned in the gun before firing said first mentioned change.

References Cited in the file of this patent UNITED STATES PATENTS 352,125 Graydon Nov. 9, 1886 380,368 Van Tine Apr. 3, 1888 694,896 Scott Mar. 4, 1902 2,156,605 Prettyman May 2, 1939 FOREIGN PATENTS 917,369 France Sept. 9, 1946 

